Dispersion resins containing itaconic acid for improving wet abrasion resistance

ABSTRACT

The invention relates to aqueous pigment preparations containing i) at least one copolymer P of ethylenically unsaturated monomers M in the form of an aqueous polymer dispersion which contains between 0.1 and 1.5 weight %, in relation to the total weight of the copolymer P, of polymerized itaconic acid as acid monomer M1, its salts and/or anhydride, where up to 50 weight % of the itaconic acid can be substituted by another monomer having at least one acid group or a neutralized acid group, and whose glass transition temperature T G  lies between −10 and +50° C.; ii) at least one inorganic pigment; iii) possibly inorganic fillers; and iv) standard additives. The invention also relates to the use of the copolymers P containing itaconic acid for improving the wet-abrasion resistance of polymer-bound coatings containing pigments.

The present invention relates to pigment-comprising aqueous formulationswhich comprise at least one aqueous addition-polymer dispersion.

Pigmented formulations are employed widely in the form of coatingcompositions, especially emulsion paints, synthetic-resin-bound plasters(dispersion plasters), sealing compounds or filling compositions forpurposes of architectural protection or decoration. Pigmentedformulations generally include as their binder a film-forming polymer,at least one inorganic pigment and, if desired, one or more inorganicfillers/extenders, and customary auxiliaries. The quality of thecoatings formed from pigmented formulations depends critically on theability of the film-forming polymer to carry out uniform binding of thenonfilm-forming constituents, the pigments and the inorganic fillers.

A low pigment binding capacity leads to poor mechanical stability of thecoating, which is manifested, for example, in a low wet abrasionresistance. The desire, however, is for high wet abrasion resistance,especially in the case of washable emulsion paints.

The pigment binding capacity of the binder plays a particularlyimportant part in formulations having a moderate to high content ofinorganic pigments and fillers/extenders. A characteristic parameter ofthe pigment content of a polymer-bound coating composition is thepigment volume concentration pvc. The pvc is usually defined as thepercentage quotient of the overall volume of solid inorganicconstituents (pigment+fillers/extenders) divided by the overall volumeof the solid inorganic constituents and of the polymer particles of theaqueous binder polymer dispersion; see Ullmanns Enzyklopädie dertechnischen Chemie, 4th edition, volume 15, p. 668.

In the case of exterior applications in particular, the coatingcompositions should be stable to environmental influences such assunlight, moisture and fluctuations in temperature. In addition, thecoating composition must adhere well to a variety of substrates evenwhen exposed to moisture, which again depends on the chosen binderpolymer.

Another property dependent on the binder polymer is the blockingresistance of the coatings.

WO 93/11181 discloses titanium dioxide-containing formulationscomprising, as dispersing auxiliaries, aqueous addition-polymerdispersions whose polymers include itaconic acid copolymerized in anamount of more than 1% by weight based on the weight of the additionpolymer. The wet abrasion resistance of the dispersions disclosedtherein leaves much to be desired.

EP-A-810 274 discloses binders for solvent-free coating compositionswhich may comprise acid-functional monomers copolymerized in an amountof up to 1% by weight based on the overall weight of the monomers to bepolymerized.

The prior art binders are able to go only some of the way toward meetingthe requirements that are placed on coating compositions.

It is an object of the present invention to provide pigmentedformulations having a high pigment binding capacity and, therefore, highwet abrasion resistance. These properties must be ensured even atrelatively high pigment volume concentrations, i.e., at pvc >40%. Theformulations should also be stable on storage—that is, their viscosityshould show little or no increase even on prolonged storage.

We have found that this object is achieved by using for the formulationsbinders based on aqueous addition-polymer dispersions whose polymerscomprise from 0.1 to 1.5% by weight of itaconic acid in copolymerizedform.

The present invention accordingly provides pigment-comprising aqueousformulations comprising

i) at least one copolymer P of ethylenically unsaturated monomers M inthe form of an aqueous polymer dispersion which comprises from 0.1 to1.5% by weight, based on the overall weight of the copolymer P, ofitaconic acid as acidic monomer M1, its salts and/or its anhydride incopolymerized form, it being possible for up to 50% by weight of theitaconic acid to be replaced by another monomer having at least one acidgroup or one neutralized acid group, and has a glass transitiontemperature T_(G) in the range from −10 to +50° C.,

ii) at least one inorganic pigment,

iii) if desired, inorganic fillers/extenders, and

iv) customary auxiliaries.

The monomers M of which the copolymer P is constructed preferably makeup from 0.2 to 1.2% by weight, in particular from 0.2 to 1.0% by weightand, with particular preference, from 0.4 to 1.0% by weight. In anespecially preferred embodiment the monomers M comprise from 0.5 to 0.9and, specifically, from 0.5 to 0.8% by weight of itaconic acid as acidicmonomer M1. Instead of itaconic acid it is also possible to employ itsanhydride or its salts to prepare the copolymers P. A certain fractionof the itaconic acid, namely up to 50% by weight, but preferably notmore than 25% by weight and in particular not more than 10% by weight,can be replaced by another monomer having at least one acid group; forexample, by an ethylenically unsaturated carboxylic acid, such asacrylic acid or methacrylic acid, or by an ethylenically unsaturatedsulfonic acid, an example being vinylsulfonic acid or its salts. Typicalsalts are the alkali metal and ammonium salts, preferably the sodiumsalts. Particular preference is given to employing itaconic acid as thesole acidic monomer (monomer M1).

Normally, the preparation of the copolymers P comprising itaconic acidtakes place by free-radical addition polymerization of ethylenicallyunsaturated monomers M which in addition to itaconic acid include atleast one further comonomer. Suitable comonomers are generally selectedfrom vinylaromatic monomers, such as styrene, α-methylstyrene,o-chlorostyrene or vinyl-toluenes, the vinyl esters of aliphatic C₁-C₁₈monocarboxylic acids, such as vinyl acetate, vinyl propionate, vinylbutyrate, vinyl valerate, vinyl hexanoate, vinyl 2-ethylhexanoate, vinyldecanoate, vinyl pivalate, vinyl laurate, vinyl stearate, and commercialmonomers VEOVA® 5-11 (VEOVA® X is a tradename of Shell and stands forvinyl esters of α-branched, aliphatic carboxylic acids having X carbonatoms, which are also referred to as versatic® X acids), and the estersof ethylenically unsaturated C₃-C₈ mono- or dicarboxylic acids withC₁-C₁₈-, preferably C₁-C₁₂-and, in particular, C₁-C₈-alkanols orC₅-C₈-cycloalkanols. Examples of suitable C₁-C₁₈-alkanols are methanol,ethanol, n-propanol, i-propanol, 1-butanol, 2-butanol, isobutanol,tert-butanol, n-hexanol, 2-ethylhexanol, lauryl alcohol and stearylalcohol. Examples of suitable cyclolkanols are cyclopentanol andcyclohexanol. Particularly suitable esters are those of acrylic acid,methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconicacid or fumaric acid. The esters concerned are especially those ofacrylic and/or methacrylic acid, such as methyl, ethyl, isopropyl,n-butyl, isobutyl, 1-hexyl, tert-butyl and 2-ethylhexyl (meth)acrylates,and also the esters of fumaric and maleic acid, examples being dimethylfumarate, dimethyl maleate and di-n-butyl maleate. Also suitable arenitriles of α,β-monoethylenically unsaturated C₃-C₈ carboxylic acids,such as acrylonitrile or methacrylonitrile. It is also possible,furthermore, to employ C₄-C₈ conjugated dienes, such as 1,3-butadiene,isoprene or chloroprene α-olefins, such as ethylene, propene andisobutene, and vinyl chloride or vinylidene chloride as comonomers.

In addition to itaconic acid the monomers M preferably include from 50to 99.9% by weight, based on the overall weight of the copolymer P, ofat least one monomer M2 selected from the abovementioned vinylaromaticmonomers, the abovementioned esters of ethylenically unsaturated C₃-C₈monocarboxylic acids with C₁-C₁₂-alkanols, and the vinyl esters ofaliphatic C₁-C₁₂ monocarboxylic acids. In a preferred embodiment of thepresent invention the monomers M2 are selected from the C₁-C₁₂-alkylesters of acrylic acid and C₁-C₁₂-alkyl esters of methacrylic acid,especially methyl methacrylate, ethyl methacrylate, n-butylmethacrylate, tert-butyl methacrylate, ethyl acrylate, n-butyl acrylate,tert-butyl acrylate and 2-ethylhexyl acrylate. Based on the overallmonomer amount, the monomers M2 make up preferably at least 80% byweight and in particular at least 90% by weight. The remainder of theabovementioned comonomers (referred to below as comonomers M′) aregenerally used in amounts <50% by weight, preferably <20% by weight and,in particular, <10% by weight, based on the overall amount of themonomers M. A preferred embodiment of this invention relates tocopolymers P which incorporate none of the abovementioned comonomers M′.

In a preferred embodiment of the invention the copolymers P comprisecopolymerized monomers M3 which have urea groups, examples beingN-vinyl- and N-allylurea and derivatives of imidazolidin-2-one, such asN-vinyl- and N-allylimidazolidin-2-one,N-vinyloxyethylimidazolidin-2-one, N-(2-(meth)acrylamidoethyl)imidazolidin-2-one, N-(2-(meth)acryloxyethyl)-imidazolidin-2-one,N-[2-((meth)acryloxyacetamido)ethyl)-imidazolidin-2-one etc. Themonomers M3 are preferably used in amounts of from 0.1 to 10% by weight,in particular from 0.5 to 5% by weight, based on the overall weight ofthe copolymer P. The monomers M3 improve the wet adhesion of thecoatings obtainable from the formulations of the invention, i.e., theadhesion of the coating in the wet or swollen state.

The copolymers P can also include in copolymerized form monomerscomprising siloxane groups (monomers M4), examples beingvinyltrialkoxysilanes, such as vinyltrimethoxysilane,alkylvinyl-dialkoxysilanes or (meth)acryloxyalkyltrialkoxysilanes, suchas (meth)acryloxyethyltrimethoxysilane, or(meth)acryloxypropyl-trimethoxysilane. The monomers M4 can be used inamounts of up to 1% by weight, preferably from 0.05 to 0.5% by weight,based on the overall monomer amount.

In addition, the copolymer P may also include in copolymerized formneutral or nonionic monomers M5 whose homopolymers feature increasedsolubility in or swellability in water. These monomers are preferablycopolymerized in amounts of <5% by weight and preferably <2% by weight,based on the overall weight of the copolymer P. Monomers of this kindenhance the stability of the polymer dispersions. Typical monomers M5are the amides, the N-alkylolamides or the hydroxyalkyl esters of theabovementioned carboxylic acids, such as acrylamide, methacrylamide,N-methylol-acrylamide, N-methylolmethacrylamide,2-hydroxyethylacrylamide, 2-hydroxyethylmethacrylamide, hydroxyethylacrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate andhydroxypropyl methacrylate.

In preparing the copolymers P it is also possible to employ bifunctionalmonomers M6. These are copolymerized if desired in minor amounts,generally from 0.1 to 5% by weight and, in particular, not more than 1%by weight, based on the overall monomer amount. Monomers M6 arepreferably monomers having two nonconjugated ethylenically unsaturatedbonds, examples being the diesters of dihydric alcohols withα,β-monoethylenically unsaturated C₃-C₈ carboxylic acids, such as glycolbisacrylate, or esters of α,β-unsaturated carboxylic acids withalkenols, such as bicyclodecenyl (meth)acrylate. Preferred polymers Pcontain no copolymerized monomers M6.

The character of the formulations of the invention is also dependent onthe glass transition temperature (DSC, midpoint temperature, ASTM D3418-82) of the copolymer P. If the glass transition temperature is toolow, the coating is not very strong and tears when subjected to amechanical load. If it is too high, the polymer no longer forms a filmand the coating, consequently, is of reduced wet abrasion resistance.The glass transition temperature of the copolymers P in question istherefore below 50° C. and preferably below 40° C., in particular below30° C. In general, however, it is above −10° C. It proves useful in thiscontext to estimate the glass transition temperature. T_(g) of thedispersed polymer. According to Fox (T. G. Fox, Bull. Am. Phys.

Soc. (Ser. II) 1, [1956]123 and Ullmanns Enzyklopädie der technischenChemie, Weinheim (1980), p. 17, 18) the glass transition temperature ofcopolymers at high molar masses is given in good approximation by$\frac{1}{T_{g}} = {\frac{X^{1}}{T_{g}^{1}} + \frac{X^{2}}{T_{g}^{2}} + {\ldots \quad \frac{X^{n}}{T_{g}^{n}}}}$

where X¹, X² . . . , X^(n) are the mass fractions of the monomers 1, 2,. . . , n and T_(g) ¹, T_(g) ², . . . , T_(g) ^(n) the glass transitiontemperatures of the homopolymers of 1, 2, . . . , n, in kelvins. Thelatter are known, for example, from Ullmann's Encyclopedia of IndustrialChemistry, VCH, Weinheim, Vol. A 21 (1992) p. 169 or from J. Brandrup,E. H. Immergut, Polymer Handbook 3^(rd) ed., J. Wiley, New York 1989.

From what has been said above it is clear that the glass transitiontemperature of the copolymer P can be adjusted both by choosing anappropriate principal monomer M2, having a glass transition temperaturewithin the desired range, and by combining at least one monomer M2ahaving a high glass transition temperature with at least one monomer M2bhaving a low glass transition temperature, the latter procedure beingpreferred.

In a preferred embodiment of the present invention the monomers M makingup the copolymer P include at least one monomer M2a whose homopolymer,for the limiting case of a very high (infinite) molecular mass, has aglass transition temperature T_(g)>30° C. and at least one monomer M2b,whose homopolymer has a glass transition temperature T_(g)<20° C.Examples of monomers M2a suitable for this purpose are styrene,α-methylstyrene, methyl methacrylate, ethyl methacrylate, n- andiso-propyl methacrylate, n-, iso- and tert-butyl methacrylate,tert-butyl acrylate and vinyl acetate, and also acrylonitrile andmethacrylonitrile, the two nitriles preferably accounting for not morethan 30% by weight of the monomers M2a. Examples of monomers M2bsuitable for this purpose are the C₁-C₁₂-alkyl acrylates, butadiene,vinyl versatates, and especially ethyl acrylate, n-butyl acrylate and2-ethylhexyl acrylate. Particular preference is given to monomercombinations M2a/M2b which comprise styrene and/or methyl methacrylateand also n-butyl acrylate with or without 2-ethylhexyl acrylate.

In one particularly preferred embodiment of the present invention thecopolymer P is constructed from:

i) from 20 to 80% by weight, preferably from 35 to 70% by weight, ofmonomers M2a, especially styrene and/or methyl methacrylate,specifically methyl methacrylate as sole monomer M2a,

ii) from 20 to 79.7% by weight, preferably from 30 to 65% by weight, ofmonomers M2b, especially n-butyl acrylate and/or ethylhexyl acrylate,

iii)from 0.1 to 1.5% by weight, preferably from 0.2 to 1.2% by weight,especially from 0.3 to 1.0% by weight and, with particular preference,from 0.5 to 0.8% by weight of itaconic acid,

iv) from 0.2 to 5% by weight, preferably from 0.5 to 3% by weight ofmonomers M3 having at least one urea group, especially an ethylenicallyunsaturated derivative of imidazolidin-2-one,

where the proportions by weight of the monomers M1, M2a, M2b and M3 addup to 100% by weight. Such copolymers P are frequently employed informulations of the invention comprising solvents.

In another preferred embodiment of the present invention the copolymer Pis constructed from:

i) from 20 to 69.7% by weight, preferably from 30 to 60% by weight, ofmonomers M2a, especially styrene and/or methyl methacrylate,specifically styrene as sole monomer M2a,

ii) from 30 to 80% by weight, preferably from 40 to 70% by weight, ofmonomers M2b, especially n-butyl acrylate and/or ethylhexyl acrylate,

iii) from 0.2 to 1% by weight, preferably from 0.4 to 0.9% by weight,especially from 0.5 to 0.8% by weight of itaconic acid,

iv) from 0.1 to 3% by weight, in particular from 0.2 to 2% by weight, ofmonomers M5, especially acrylamide and/or methacrylamide,

where the proportions by weight of the monomers M1, M2a, M2b and M5b addup to 100% by weight. Such copolymers P are frequently employed informulations of the invention that are solvent-free.

The copolymers P of the two preferred embodiments can of course bemodified with siloxane groups, by means, for example, of copolymerizedmonomers M4 (see above) or by using regulators containing siloxanegroups, examples being mercaptoalkyltri-alkoxysilanes such asmercaptopropyltrimethoxysilane.

It has additionally proven advantageous if the polymer particles in thebinder polymer dispersion have a ponderal median polymer particlediameter in the range from 50 to 1000 nm (determined by means of anultracentrifuge or by photon correlation spectro-scopy; regarding thedetermination of particle size by means of an ultra-centrifuge see, forexample, W. Mächtle, Makromolekulare Chemie 185, (1984) 1025-1039 and W.Mächtle, Angew. Makromolekulare Chemie 162 (1988) 35-42). In the case ofbinder dispersions with high solids contents, such as >50% by weight,based on the overall weight of the binder dispersion, it is advantageouson grounds of viscosity for the ponderal median diameter of the polymerparticles in the dispersion to be ≧250 nm. The median particle diameterwill generally not exceed 1000 nm and preferably will not exceed 600 nm.

The aqueous polymer dispersions employed in accordance with theinvention are preferably prepared by free-radical aqueous emulsionpolymerization of the abovementioned monomers in the presence of atleast one free-radical polymerization initiator and, if desired, of asurface-active substance.

Suitable free-radical polymerization initiators are all those capable oftriggering a free-radical aqueous emulsion polymerization reaction. Theycan be peroxides, for example, alkali metal peroxodisulfates, or azocompounds. As polymerization initiators it is common to use redoxinitiators, which are composed of at least one organic reducing agentand at least one peroxide and/or hydroperoxide, examples beingtert-butyl hydroperoxide with sulfur compounds, such as the sodium saltof hydroxymethanesulfinic acid, sodium sulfite, sodium disulfite, sodiumthiosulfate or acetone bisulfite adduct, or hydrogen peroxide withascorbic acid. Use is also made of combined systems which comprise asmall amount of a metal compound which is soluble in the polymerizationmedium and whose metal component can exist in a plurality of valencestates, an example of such a system being ascorbic acid/iron(II)sulfate/hydrogen peroxide, where the ascorbic acid is frequentlyreplaced by the sodium salt of hydroxymethanesulfinic acid, acetonebisulfite adduct, sodium sulfite, sodium hydrogen sulfite or sodiumbisulfite, and the hydrogen peroxide by organic peroxides, such astert-butyl hydroperoxide, or alkali metal peroxodisulfates and/orammonium peroxodisulfate. Initiators which are likewise preferred areperoxodisulfates, such as sodium peroxodisulfate. The amount of thefree-radical initiator system that is employed, based on the overallamount of monomers to be polymerized, is preferably from 0.1 to 2% byweight.

Surface-active substances suitable for conducting the emulsionpolymerization are the emulsifiers and protective colloids commonlyemployed for this purpose. The surface-active substances are normallyemployed in amounts of up to 10% by weight, preferably from 0.5 to 5% byweight and, in particular, from 1 to 4% by weight, based on the monomersto be polymerized.

Examples of suitable protective colloids are polyvinyl alcohols, starchderivatives and cellulose derivatives, or vinylpyrrolidone copolymers.An exhaustive description of further suitable protective colloids isgiven in Houben-Weyl, Methoden der organischen Chemie, Volume XIV/1,Makromolekulare Stoffe [Macromolecular substances], Georg-Thieme-Verlag,Stuttgart 1961, pp. 411-420.

As surface-active substances it is preferred to employ exclusivelyemulsifiers, whose relative molecular weights, unlike those of theprotective colloids, are usually below 2000. They can be anionic ornonionic in nature. The anionic emulsifiers include alkali metal saltsand ammonium salts of alkyl sulfates (alkyl: C₈-C₁₂), of sulfuricmonoesters with ethoxylated alkanols (EO units: 2 to 50, alkyl: C₁₂ toC₁₈) and with ethoxylated alkylphenols (EO units: 3 to 50, alkyl:C₄-C₉), of alkylsulfonic acids (alkyl: C₁₂-C₁₈) and of alkylarylsulfonicacids (alkyl: C₉ to C₁₈), and also compounds of the general formula I,

where R¹ and R² are hydrogen or C₄-C₂₄-alkyl, preferably C₈-C₁₆-alkyl,but are not both hydrogen and X and Y can be alkali metal ions and/orammonium ions. Use is frequently made of technical-grade mixtures whichhave a proportion of from 50 to 90% by weight of the monoalkylatedproduct, an example being Dowfax® 2A1 (R¹=C₁₂-alkyl; DOW CHEMICAL). Thecompounds I are widely known, from U.S. Pat. No. 4,269,749, for example,and are obtainable commercially.

Suitable nonionic emulsifiers are araliphatic or aliphatic nonionicemulsifiers, examples being ethoxylated mono-, di- and trialkylphenols(EO units: 3 to 50, alkyl: C₄-C₉), ethoxylates of long-chain alcohols(EO units: 3 to 50, alkyl: C₈-C₃₆), and polyethylene oxide/polypropyleneoxide block copolymers. Preference is given to ethoxylates of long-chainalkanols (alkyl: C₁₀-C₂₂, average degree of ethoxylation: 3 to 50) and,of these, particular preference to those based on naturally occurringalcohols or on oxo alcohols having a linear or branched C₁₂-C₁₈-alkylradical and a degree of ethoxylation of from 8 to 50. Preference isgiven to anionic emulsifiers or to combinations of at least one anionicand one nonionic emulsifier.

Further suitable emulsifiers are given in Houben-Weyl, op. cit. pp.192-208.

The molecular weight of the copolymers P can be adjusted by adding smallamounts, generally up to 2% by weight based on the monomers to bepolymerized, of one or more molecular weight regulators, examples beingorganic thiocompounds, silanes, allyl alcohols, and aldehydes.

The emulsion polymerization can be conducted either continuously or bythe batch procedure, preferably by a semicontinuous process. Insemicontinuous processes the major amount—that is, at least 70%,preferably at least 90% of the monomers to be polymerized—is suppliedcontinuously, including by a staged or gradient procedure, to thepolymerization batch. This procedure is also referred to as the monomerfeed process. It has been found advantageous in this context for themajor amount of the itaconic acid—that is, at least 50%, preferably atleast 80%, in particular at least 90% and, with very particularpreference, all of the itaconic acid to be supplied to thepolymerization reaction by way of the monomer feed; in other words, nomore than 50% of the itaconic acid and, with very particular preference,no itaconic acid is included in the initial charge to the polymerizationvessel before the polymerization is begun. By monomer feeds are meantliquid monomer mixtures, monomer solutions or, in particular, aqueousmonomer emulsions.

In addition to the seed-free preparation method it is also possible, inorder to establish a defined polymer particle size, to conduct theemulsion polymerization by the seed latex process or in the presence ofa seed latex prepared in situ. Processes for this purpose are known andcan be found in the prior art (see EP-B 40419, EP-A-614 922, EP-A-567812 and literature cited therein and also Encyclopedia of PolymerScience and Technology′, Vol. 5, John Wiley & Sons Inc., New York 1966,p. 847).

The polymerization is preferably conducted in the presence of from 0.01to 3% by weight and, in particular, from 0.02 to 1.5% by weight of aseed latex (solids content of the seed latex, based on overall monomeramount), preferably with a seed latex included in the initial charge(initial charge seed).

The preparation of the aqueous dispersions of the copolymers P can alsobe carried out by what is known as staged polymerization. This means aprocedure in a 1st stage of which the monomers of the 1st stage arepolymerized by free-radical aqueous emulsion polymerization, preferablyin the presence of a seed latex, after which the monomers of the 2ndstage are polymerized in the aqueous dispersion of the resultant1st-stage polymer. This may be followed by further polymerizationstages. In such a procedure, the monomer mixtures of the 1st stage andof the 2nd stage differ in the nature of the monomers and/or in therelative proportions of the monomers. The nature of the monomers to bepolymerized in the 1st and 2nd stages is preferably the same. Where themonomers M include both a monomer M2a and a monomer M2b, the monomermixtures of the 1st stage differ from those of the 2nd stage by theproportion M2a/M2b. In particular, the proportion M2a/M2b in the 1ststage is greater than the proportion M2a/M2b in the 2nd stage. Theproportion of the monomers of the 1st stage to the monomers of the 2ndstage lies preferably within the range from 1:10 to 10:1 and, inparticular, in the range from 1:5 to 5:1. Staged polymerization achievesthe polymerization of the monomers of the 2nd stage (and, whereappropriate, of subsequent stages) onto the polymer particles of the 1ststage.

The pressure and temperature of polymerization are of minor importance.It is normal to operate at temperatures of between room temperature and120° C., preferably at temperatures from 40 to 95° C. and, withparticular preference, between 50 and 90° C.

Following the polymerization reaction proper, it may be necessary torender the aqueous polymer dispersions of the invention substantiallyfree from odoriferous substances, such as residual monomers and othervolatile organic constituents. This can be done physically in a mannerknown per se, by distillative removal (especially by steamdistillation), or by stripping with an inert gas. The residual monomercontent can also be lowered chemically by means of free-radicalpostpolymerization, especially under the action of redox initiatorsystems, as are set out, for example, in DE-A 44 35 423.Postpolymerization is preferably conducted with a redox initiator systemcomprising at least one organic peroxide and one organic sulfite.

The dispersions of the copolymer P are preferably adjusted to a pH inthe range from 6 to 10 before being used in the formulations of theinvention, preferably by adding a nonvolatile base, examples beingalkali metal hydroxides, alkaline earth metal hydroxides or nonvolatileamines.

By the method of emulsion polymerization it is possible in principle toobtain dispersions having solids contents of up to about 80% by weight(polymer content based on the overall weight of the dispersion). Forpractical reasons it is generally preferred to use polymer dispersionshaving solids contents in the range from 40 to 70% by weight for theformulations of the invention. Particular preference is given todispersions having polymer contents of about 50% by weight. Dispersionshaving lower solids contents are of course suitable in principle for usefor the formulations of the invention.

In accordance with the invention the copolymers P comprising itaconicacid are employed in the form of their aqueous polymer dispersions asbinders in pigmented formulations that are used to coat substrates.Examples of what are meant by such formulations include polymerdispersion plasters, tile adhesives, paints and varnishes, and sealantsor sealing compounds, especially for porous components.

A preferred embodiment of the present invention relates to formulationsin the form of emulsion paints.

The formulations of the invention, preferably emulsion paints, generallycontain from 30 to 75% by weight and, preferably, from 40 to 65% byweight, of nonvolatile constituents. By these are meant all thoseconstituents of the formulation except for water, but at least the totalamount of binder, extender, pigment, solvents of low volatility (boilingpoint above 220° C.), such as plasticizers, and polymeric auxiliaries.Of these, the amounts accounted for by each class of constituent are

from 3 to 90% by weight, preferably from 10 to 60% by weight, by solidbinder constituents (=copolymer P),

ii from 5 to 85% by weight, preferably from 10 to 60% by weight, by atleast one inorganic pigment,

iii from 0 to 85% by weight, preferably from 20 to 70% by weight, byinorganic fillers, and

iv from 0.1 to 40% by weight, preferably from 0.5 to 15% by weight, bycustomary auxiliaries.

The pvc of the formulations is generally above 10%, for example from 15to 85%. In one preferred embodiment of the invention it is within therange from 15 to 25%. In another preferred embodiment of the inventionthe pvc is in the range from >40% to 60% by weight, e.g., at about 45%by weight. In a further preferred embodiment of the invention the pvcis >60%, preferably >70%, and can be up to 85%.

Typical pigments for the formulations of the invention, especially foremulsion paints, are, for example, titanium dioxide, preferably in therutile form, barium sulfate, zinc oxide, zinc sulfide, basic leadcarbonate, antimony trioxide, and lithopones (zinc sulfide+bariumsulfate). However, the formulations may also comprise color pigments,examples being iron oxides, carbon black, graphite, luminescentpigments, zinc yellow, zinc green, ultramarine, manganese black,antimony black, manganese violet, Paris blue or Schweinfurt green. Inaddition to the inorganic pigments the formulations of the invention mayalso include organic color pigments, examples being sepia, gamboge,Cassel brown, toluidine red, para red, Hansa yellow, indigo, azo dyes,anthraquinonoid and indigoid dyes, and also dioxazine, quinacridone,phthalocyanine, isoindolinone and metal complex pigments.

Suitable fillers include, in principle, alumosilicates, such asfeldspars, silicates, such as kaolin, talc, mica, magnesite, alkalineearth metal carbonates, such as calcium carbonate, in the form, forexample, of calcite or chalk, magnesium carbonate, dolomite, alkalineearth metal sulfates, such as calcium sulfate, silicon dioxide, etc. Thefillers can be employed as individual components. In practice, however,filler mixtures have proven especially suitable, such as calciumcarbonate/kaolin and calcium carbonate/talc. Dispersion plasters mayalso include relatively coarse aggregates, such as sands or sandstonegranules. In emulsion paints, of course, finely divided fillers arepreferred.

To increase the hiding power and to save on the use of white pigments itis common in the preferred emulsion paints to employ finely dividedfillers (extenders), examples being finely divided calcium carbonate ormixtures of different calcium carbonates having different particlesizes. To adjust the hiding power, the shade and the depth of color itis preferred to employ blends of color pigments and extenders.

The customary auxiliaries iv include wetting agents or dispersants, suchas sodium, potassium or ammonium polyphosphates, alkali metal salts andammonium salts of polyacrylic acids and of polymaleic acid,polyphosphonates, such as sodium 1-hydroxyethane-1,1-diphosphonate, andsalts of naphthalenesulfonic acids, especially their sodium salts. Thedispersants are generally employed in an amount of from 0.1 to 0.6% byweight based on the overall weight of the emulsion paint.

The auxiliaries iv may also include thickeners, examples being cellulosederivatives, such as methylcellulose, hydroxyethyl-cellulose andcarboxymethylcellulose, and also casein, gum arabic, tragacanth gum,starch, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, sodiumpolyacrylates, water-soluble copolymers based on acrylic and methacrylicacid, such as acrylic acid-acrylamide and methacrylic acid-acrylatecopolymers, and what are known as associative thickeners, examples beingstyrene-maleic anhydride polymers or, preferably, hydrophobicallymodified polyetherurethanes, as are described, for example, by N. Chenet al. in J. Coatings Techn. Vol 69, No. 867, 1997, p. 73 and by R. D.Hester et al. in J. Coatings Technology, Vol. 69, No. 864, 1997, 109,the content of which is hereby incorporated in its entirety byreference.

Examples of hydrophobically modified polyetherurethanes are polymers ofthe general formula II

where R^(f) is a hydrophobic radical, preferably a linear or branchedalkyl of 10 to 20 carbon atoms, Et is 1,2-ethylene, Sp isC₂-C₁₀-alkylene, cycloalkylene or arylene, k is from 50 to 1000 and l isfrom 1 to 10, the product k×l preferably being from 300 to 1000. Thedispersants and/or wetting agents are employed in general in an amountof from 0.1 to 0.6% by weight, based on the overall weight of theemulsion paint.

Inorganic thickeners, such as bentonites or hectorite, can also be used.Thickeners are generally used in amounts of from 0.1 to 3% by weight,preferably from 0.1 to 1% by weight, based on the overall weight of theaqueous formulation. In addition, the auxiliaries iv generally alsoinclude defoamers, preservatives or hydrophobicizing agents, biocides,fibers or other constituents.

In addition, in order to adjust the film-forming properties of thebinder polymers, the coating compositions may also comprise what areknown as film-forming consolidating agents (plasticizers), examplesbeing ethylene glycol, propylene glycol, butylene glycol, hexyleneglycol, alkyl ethers and alkyl ether esters of glycols and polyglycols,e.g., diethylene glycol monoethyl ether, diethylene glycol monoethylether acetate, diethylene glycol monobutyl ether, hexylene glycoldiacetate, propylene glycol monoethyl ether, monophenyl ether, monobutylether and monopropyl ether, dipropylene glycol monomethyl ether, andmono-n-butyl ether, tripropylene glycol mono-n-butyl ether, and theacetates of said monoalkyl ethers, such as butoxybutyl acetate, and alsoalkyl esters of aliphatic mono- and dicarboxylic acids, such as Texanol®from Eastman, or technical-grade mixtures of dibutyl esters of succinic,glutaric and adipic acid. Film-forming auxiliaries are customarilyemployed in amounts of from 0.1 to 20% by weight, based on the copolymerP present in the formulation, so that the formulation has a minimumfilm-forming temperature of <15° C. and preferably in the range from 0to 10° C.

A distinction is often made between solventborne and solventless paints.Solventborne paints are preferably employed for exterior applicationsand solventless paints preferably for interior applications. Typicalsolventborne paints include not only the abovementioned film-formingauxiliaries but also, for the same purpose, hydrocarbons and/or mixturesthereof, with or without aromatic constituents, such as white spirits inthe boiling range from 140 to 210° C. The copolymers P in solventborneformulations often have a glass transition temperature T_(G) ≧5° C. and,preferably, ≦30° C. In solventless paints the glass transitiontemperature is preferably ≦10° C.

Furthermore, the formulations employed in accordance with the inventionmay also include crosslinking additives. Additives of this kind can bearomatic ketones, such as alkyl phenyl ketones unsubstituted or with oneor more substituents on the phenyl ring, or benzophenone and substitutedbenzophenones, as photoinitiators. Photoinitiators suitable for thispurpose are known, for example, from DE-A-38 27 975 and EP-A-417 568.Other suitable crosslinking compounds are water-soluble compounds havingat least two amino groups, examples being dihydrazides of aliphaticdicarboxylic acids in accordance with DE-A-39 01 073, if the copolymer Pcomprises carbonyl-containing monomers in copolymerized form.

The formulations of the invention are stable fluid systems which can beused to coat a large number of substrates. Accordingly, the presentinvention also provides a method of coating substrates. Examples ofsuitable substrates are wood, concrete, metal, glass, ceramics, plastic,plaster, wallpaper and coated, primed or weathered substrates. Theformulation is applied to the target substrate in a manner dependent onthe form of the formulation. Depending on the viscosity and pigmentcontent of the formulation and on the substrate, application may takeplace by means of rolling, brushing, knife coating or spraying.

The coatings produced using the formulations of the invention arenotable for high wet abrasion resistance and good adhesion under dampconditions, i.e., in the wet or swollen state. An improved wet abrasionresistance—in other words, an improved mechanical stability of thecoatings toward abrasive influences in the damp state—is favorable forthe weathering stability and wet cleaning stability of the coatings andtherefore means that they can be washed. Moreover, the coatings are nottacky, and feature high blocking resistance.

The advantageous properties of the copolymer P as binder relative toprior art binder polymers, and especially its improved wet abrasionresistance, is equally in evidence in the case of pigmented formulationshaving a pvc of <40% and in the case of formulations having a pvcof >40% or a pvc of >60%. The advantages of the invention becomeparticularly evident if the formulations have a pvc of >40% and up to85%, for example, a pvc of about 45% or a pvc of from 70 to 80%.Accordingly, the present invention also provides for the use of thecopolymers P to improve the wet abrasion resistance ofpigment-comprising formulations.

The examples below are intended to illustrate the invention withoutrestricting it.

I. Preparing and Characterizing the Polymer Dispersions (Copolymers P)

The average particle size (z-average) of the polymer particles was foundby dynamic light scattering (photon correlation spectroscopy) on a 0.01%by weight dispersion in water at 23° C. using an Autosizer IIc fromMalvern Instruments, England. The value stated is the cumulant z-averageof the measured autocorrelation function.

The minimum film-forming temperature (MFT) of the polymer dispersionswas determined in accordance with Ullmanns Enzyklopädie der technischenChemie, 4th ed., Vol. 19, VCH Weinheim 1980, p. 17. The measuring deviceused was a film formation bench (a metal plate to which a temperaturegradient is applied and on which temperature sensors are mounted atdifferent points for the purpose of temperature calibration, thetemperature gradient being chosen such that one end of the filmformation bench has a temperature above the anticipated MFT and theother end has a temperature below the anticipated MFT). The aqueouspolymer dispersion is then applied to the film formation bench. In thoseregions of the film formation bench whose temperature is above the MFTthe dispersion dries to form a clear film whereas in the cooler regionscracks appear in the film and at lower temperatures still it forms awhite powder. The MFT is determined visually on the basis of the knowntemperature profile of the plate.

1. Comparative Dispersion CD1

A reactor was charged with 234 g of deionized water, 38 g of aqueoussodium pyrophosphate solution (5% strength by weight) and 4.61 g of apolystyrene seed latex (particle size about 30 nm, solids content about33% by weight). This initial charge was heated to 85° C. under nitrogen.Then 7.24 g of aqueous initiator solution were added. A monomer emulsionwas then added over the course of 3 hours, and the remainder of theinitiator solution over the course of 4 hours. After the end of theaddition of initiator the temperature was maintained for 1 hour and thenlowered to 60° C. Subsequently, 6.36 g of a 15% strength by weightaqueous solution of tert-butyl hydroperoxide and 7.25 g of an aqueous13.1% strength by weight solution of acetone bisulfite were supplied tothe reactor by way of separate feeds. The 60° C. were maintained for 1hour. The batch was then cooled to room temperature and its pH adjustedto 7.4 using 10% strength by weight sodium hydroxide solution. Theresulting dispersion was free from coagulum and had a solids content of60.1% by weight. The ponderal median particle diameter of the polymerwas 270 nm. Its MFT was 6° C.

Initiator solution: 2.38 g of sodium peroxodisulfate

70.00 g of deionized water

Monomer emulsion: 227.73 g of deionized water

21.11 g of emulsifier solution 1

47.50 g of emulsifier solution 2

356.25 g of methyl methacrylate

502.55 g of n-butyl acrylate

19.00 g of methacrylic acid

72.20 g of a 25% strength by weight solution of N-(methacryloxyethyl)imidazolidin-2-one in methyl methacrylate

Emulsifier solution 1: 45% strength by weight solution of sodium(dodecylsulfonylphenoxy) benzenesulfonate (Dowfax® 2A1 from DowChemicals) in water

Emulsifier solution 2: 30% strength by weight solution of the sodiumsalt of a sulfuric monoester mixture of C₁₀-C₁₆-alkyl ethoxylates(average EO units 30) in water (Disponil® FES 77 from Henkel KGaA).

2. Comparative Dispersion CD2

In the manner described for CD1 but with a different monomer compositiona comparative dispersion CD2 was prepared. Instead of the polystyreneseed latex the initial charge contained 19 g of acrylate latex (50%strength by weight, d₅₀=130 nm). Following the polymerization reaction,the pH was adjusted to 7.0 using 10% strength by weight sodium hydroxidesolution. The resulting dispersion was free from coagulum and had asolids content of 58.7% by weight. The average diameter of the polymerparticles was 235 nm. The MFT was 4° C.

Monomer emulsion: 226.41 g of water

21.11 g of emulsifier solution 1

47.50 g of emulsifier solution 2

356.25 g of methyl methacrylate

502.55 g of n-butyl acrylate

19.00 g of itaconic acid

72.20 g of a 25% strength by weight solution of N-(methacryloxyethyl)imidazolidin-2-one in methyl methacrylate.

3. Comparative Dispersion CD3

A reactor was charged with 175 g of deionized water, 38 g of aqueoussodium pyrophosphate solution (5% strength by weight) and 3.80 g of apolystyrene seed latex (particle size about 30 nm, solids content about5% by weight). This initial charge was heated to 85° C. under nitrogen.Then 7.24 g of aqueous initiator solution were added. A monomer emulsionwas then added over the course of 3 hours, and the remainder of theinitiator solution over the course of 4 hours. After the end of theaddition of initiator the temperature was maintained for 1 hour and thenlowered to 60° C. Subsequently, 1.36 g of a 15% strength by weightaqueous solution of tert-butyl hydroperoxide and 7.25 g of an aqueous13.1% strength by weight solution of acetone bisulfite were supplied tothe reactor by way of separate feeds. The 60° C. were maintained for 1hour. The batch had its pH adjusted to 8.5 using 10% strength by weightsodium hydroxide solution. The resulting dispersion was free fromcoagulum and had a solids content of 52.8% by weight. The ponderalmedian particle diameter was 280 nm. Its MFT was 2° C.

Initiator solution: 2.38 g of sodium peroxodisulfate

70.00 g of deionized water

Monomer emulsion: 379.15 g of deionized water

63.33 g of emulsifier solution 3

118.75 g of emulsifier solution 4

391.88 g of methyl methacrylate

513.00 g of n-butyl acrylate

19.00 g of itaconic acid

38.00 g of a 25% strength by weight solution of N-(methacryloxyethyl)imidazolidin-2-one in methyl methacrylate.

Emulsifier solution 3: 15% strength by weight solution of sodiumdodecylbenzenesulfonate in water

Emulsifier solution 4: 20% strength by weight solution of an ethoxylatedC₁₆-C₁₈ fatty alcohol (18 EO units)

4. Comparative Dispersion CD4

A polymerization reactor was charged with 235 g of deionized water and3.8 g of polystyrene seed latex (5% strength by weight, d₅₀=30 nm) andthis initial charge was flushed with nitrogen and heated to 85° C. Then7.24 g of aqueous initiator solution were added. Subsequently, still at85° C., the monomer emulsion I was added over the course of 3 h and theinitiator solution over the course of 4 h. After the end of the additionof the monomer emulsion I the monomer emulsion II was introduced intothe reactor over the course of 1 h. After the end of the addition ofinitiator and monomer the 85° C. were maintained for a further hour andthe batch was then cooled to 60° C. Then, at 60° C., 1.36 g of a 15%strength by weight aqueous solution of tert-butyl hydroperoxide and 7.25g of a 13.1% strength by weight aqueous solution of acetone bisulfitewere introduced into the reactor by way of separate feeds and the 60° C.were maintained for 1 hour. The batch was then cooled to roomtemperature and its pH was adjusted to 8.5 using 10% strength by weightsodium hydroxide solution. The dispersion was free from coagulum and hada solids content of 63.9% by weight. The average polymer particlediameter was 270 nm and the minimum film-forming temperature of thedispersion was 13° C.

Initiator solution: 2.38 g of sodium peroxodisulfate

70.00 g of deionized water

Monomer emulsion I: 47.84 g of deionized water

66.50 g of emulsifier solution 3 (see CD3)

66.50 g of emulsifier solution 4 (see CD3)

14.25 g of 10% strength by weight sodium hydroxide solution

332.03 g of methyl methacrylate

312.55 g of n-butyl acrylate

4.75 g of acrylic acid

9.75 g of a 25% strength by weight solution ofN-(methacryloxyethyl)-imidazolidin-2-one in methyl methacrylate

Monomer emulsion II: 16.98 g of deionized water

28.50 g of emulsifier solution 3

28.50 g of emulsifier solution 4

108.20 g of methyl methacrylate

140.41 g of n-butyl acrylate

2.38 g of acrylic acid

28.50 g of a 25% strength by weight solution of N-(methacryloxyethyl)imidazolidin-2-one in methyl methacrylate

5. Comparative Dispersion CD5

CD5 was prepared in analogy to CD4 but replacing the acrylic acid byequal amounts of methacrylic acid. Following the polymerization, the pHwas adjusted to 8.6. The dispersion was free from coagulum and had asolids content of 62.8% by weight. The ponderal median polymer particlediameter was 272 nm and the minimum film-forming temperature was 10° C.

6. Dispersion D1 (Inventive)

The inventive dispersion D1 was prepared in analogy to the comparativedispersion CD3. The monomer emulsion had the following composition:

117.74 g of deionized water

63.33 g of emulsifier solution 3

118.75 g of emulsifier solution 4

391.88 g of methyl methacrylate

513.00 g of n-butyl acrylate

9.50 g of itaconic acid

38.00 g of a 25% strength by weight solution ofN-(methacryloxyethyl)imidazolidin-2-one in methyl methacrylate

Following its preparation, the pH of the dispersion was adjusted to 8.7using 10% strength by weight sodium hydroxide solution. The resultingdispersion was free from coagulum and had a solids content of 62.8% byweight. The ponderal median polymer particle diameter was 311 nm, theMFT 4.0° C.

7. Dispersion D2

The inventive dispersion D2 was prepared in analogy to the comparativedispersion CD2.

The monomer emulsion had the following composition:

230.96 g of deionized water

21.11 g of emulsifier solution 1 (see CD1)

47.50 g of emulsifier solution 2 (see CD1)

356.25 g of methyl methacrylate

502.55 g of n-butyl acrylate

9.50 g of itaconic acid

72.20 g of 25% strength by weight solution of N-(methacryloxyethyl)imidazolidin-2-one in methyl methacrylate

Following the polymerization the dispersion was neutralized to a pH of7.0 with 10% strength by weight sodium hydroxide solution. The resultingdispersion was virtually free from coagulum and had a solids content of58.7% by weight. The average polymer particle diameter was 235 nm, theMFT was 4.0° C.

8. Dispersion D3

The inventive dispersion D3 was prepared in analogy to the comparativedispersion CD3. The monomer emulsion had the following composition:

92.62 g of deionized water

63.33 g of emulsifier solution 3 (see CD3)

118.75 g of emulsifier solution 4 (see CD3)

391.88 g of methyl methacrylate

513.00 g of n-butyl acrylate

7.13 g of itaconic acid

38.00 g of a 25% strength by weight solution of N-(methacryloxyethyl)imidazolidin-2-one in methyl methacrylate

The dispersion was neutralized to a pH of 9.5 with 10% strength byweight sodium hydroxide solution. The resulting dispersion was free fromcoagulum and had a solids content of 64.9% by weight. The averagepolymer particle diameter was 285 nm, the MFT was 2.0° C.

9. Dispersion D4

The inventive dispersion D4 was prepared in analogy to the comparativedispersion CD4.

Monomer emulsion I: 47.84 g of deionized water

66.50 g of emulsifier solution 3 (see CD3)

66.50 g of emulsifier solution 4 (see CD3)

14.25 g of 10% strength by weight sodium hydroxide solution

332.03 g of methyl methacrylate

312.55 g of n-butyl acrylate

4.75 g of itaconic acid

9.50 g of a 25% strength by weight solution of N-(methacryloxyethyl)imidazolidin-2-one in methyl methacrylate

Monomer emulsion II: 16.98 g of deionized water

28.50 g of emulsifier solution 3

28.50 g of emulsifier solution 4

108.02 g of methyl methacrylate

140.41 g of n-butyl acrylate

2.38 g of itaconic acid

28.50 g of a 25% strength by weight solution of N-(methacryloxyethyl)imidazolidin-2-one in methyl methacrylate.

10. Dispersion D5

The inventive dispersion D5 was prepared in analogy to the dispersion D4except that all of the itaconic acid in the monomer emulsion II wasreplaced by acrylic acid. The MFT of the dispersion was 10° C.

11. Comparative Dispersions CD6, CD7 and Dispersion D6

A polymerization reactor was charged with 200 g of deionized water, 0.1g of formic acid, 7.5 g of emulsifier solution 4 (see CD3), 1.5 g ofstearyl alcohol and 40 g of monomer emulsion and this initial charge washeated to 85° C. under nitrogen. Then, at 85° C., 10 g of initiatorsolution were introduced into the polymerization reactor. 15 minutesafter the addition of initiator the remainder of the monomer emulsionwas added over the course of 120 minutes and the remainder of theinitiator solution over the course of 135 minutes, these additions tothe polymerization reactor beginning simultaneously but taking place byway of separate feeds and still at 85° C. After the end of the additionof initiator the 85° C. were maintained for a further 2 h, the batch wascooled to 70° C., and then 0.71 g of a 70% strength by weight aqueoussolution of tert-butyl hydroperoxide was introduced into thepolymerization reactor. This was followed by the metered addition over30 minutes at 70° C. of 5 g of a 10% strength by weight aqueous solutionof hydroxymethanesulfinic acid, as the sodium salt. The dispersion wassubsequently cooled to room temperature, 12 g of 10% strength by weightsodium hydroxide solution were added, and the dispersion was filteredthrough a sieve having a mesh size of 250 μm.

Initiator solution: 1.50 g of sodium peroxodisulfate

100.00 g of deionized water

Monomer emulsion: 120.00 g of deionized water

20.00 g of emulsifier solution 1 (see CD1)

80.00 g of emulsifier solution 4 (see CD3)

26.70 g of 15% strength by weight aqueous sodium lauryl sulfate solution

5.00 g of polymerizable acid (Table 1)

1.00 g of mercaptopropyltrimethoxysilane

15.00 9 of 50% strength by weight aqueous acrylamide solution

200.00 g of styrene

300.00 g of n-butyl acrylate

TABLE 1 SC LT Dispersion polymerizable acid [% by wt.] [%] CD6 Acrylicacid 48.9 68 CD7 Methacrylic acid 49.2 72 D6 Itaconic acid 49.7 73 SC =Solids content of the dispersion LT = Light transmittance of a samplediluted to 0.01% by weight, path length 2.5 cm, relative to water

12. Dispersions CD8, CD9 and D7

The dispersions CD8, CD9 and D7 were prepared in analogy to dispersionsCD6, CD7 and D6. The following components were included in the initialcharge:

200.00 g of deionized water

12.50 g of emulsifier solution 4 (see CD3)

5.00 g of emulsifier solution 1, 20% strength by weight (see CD1)

37.00 g of monomer emulsion

The monomer emulsion had the following composition:

170.00 g of deionized water

35.00 g of emulsifier solution 1, 20% strength by weight (see CD1)

25.00 g of emulsifier solution 4 (see CD3)

x g polymerizable acid (see Table 2)

y g of 50% strength by weight aqueous acrylamide solution

250.00 g of styrene

250.00 g of n-butyl acrylate

Following the polymerization the dispersion was neutralized to a pH of7.5 with 10% strength sodium hydroxide solution and filtered through ametal sieve having a mesh size of 250 μm.

TABLE 2 polymerizable acid Acrylamide solution SC LT Dispersion [g] [g][%] [%] CD8 Methacrylic acid; 15.0 49.1 65 13.5 CD9 Acrylic acid 15.049.9 68 13.5 D7 Itaconic acid 0 49.2 71  5.0 SC = Solids content of thedispersion LT = Light transmittance of a sample diluted to 0.01% byweight, path length 2.5 cm, relative to water

II. Preparing the Formulations of the Invention

1. Emulsion paints with a pvc of 46.9%; formulation (I) (comparativeexamples C1 to C5, Inventive Examples 1 to 5)

A vessel was charged with the following constituents:

105.60 g of water

2.00 g of thickener¹⁾

0.80 g of 2-amino-2-methylpropanol with 5% water

1.00 g of dispersant²⁾

3.40 g of 10% strength by weight aqueous tetrapotassium pyrophosphatesolution

1.70 g of commercial biocide³⁾

3.40 g of commercial defoamer⁴⁾

10.10 g of propylene glycol and

10.10 g of dipropylene glycol n-butyl ether.

1) Hydroxyethylcellulose having a viscosity of 30 Pas (determined as 2%strength solution in water at 25° C.); Natrosol® 250 HR from HerculesGmbH, Düsseldorf

2) 30% strength by weight aqueous solution of an ammonium polyacrylate;Pigmentverteiler [pigment dispersant] A from BASF AG, Ludwigshafen

3) Proxel®GXL from zeneca GmbH, Frankfurt

4) Foammaster®S from Henkel KGaA, Düsseldorf

The following constituents were added with stirring:

190.10 g of titanium dioxide pigment⁵⁾

181.60 g of feldspar⁶⁾ and

50.70 g of calcined kaolin⁷⁾

5) Kronos®2101 from Kronos, Houston/Tex.

6) Minex®4 from Unimin Speciality Minerals Inc. Elco/Illinois, averageparticle size 7.5 μm

7) Icecap® from Burgess Pigment Co., Sandersville, Ga.

The constituents were mixed for 20 minutes in a high-speed disperser.Then the following constituents were added with stirring:

266.01 g of polymer dispersion from I)

2.50 g of commercial defoamer⁴⁾

11.80 g of commercial thickener⁸⁾

159.00 g of water.

4) Foammaster®S from Henkel KGaA, Düsseldorf

8) 20% strength by weight solution of an associatively thickeningpolyurethane, Acrysol RM 2020 from Rohm and Haas Deutschland GmbH,Frankfurt

The performance properties of the emulsion paints are summarized inTables 3 and 4.

2. Solventless Interior Paint with a pvc of 75%, Formulation II(Comparative Examples C6 and C7 and Inventive Example 6)

A vessel was charged with the following constituents:

106.00 g of water

1.00 g of 20% strength by weight sodium hydroxide solution

3.00 g of 35% strength by weight solution of a sodium polyphosphate inwater²²⁾

3.00 g of dispersing auxiliary⁹⁾

3.00 g of preservative¹⁰⁾

4.00 g of defoamer¹¹⁾

180.00 g of 2% strength by weight aqueous hydroxyethyl-cellulosesolution¹⁾

22) Calgon® from BK Ladenburg, Ladenburg

9) 35% strength by weight aqueous solution of a sodium polyacrylate;Pigmentverteiler [pigment dispersant] NL from BASF AG, Ludwigshafen

10) Parmetol®A23 from Schulke & Mayr GmbH, Norderstedt

11) Agitan 280 from Münzing-Chemie GmbH, Heilbronn

1) Bydroxyethylcellulose having a viscosity of 30 Pas (determined as 2%strength solution in water at 25° C.); Natrosol® 250 HR from HerculesGmbH, Düsseldorf

The following constituents were added with stirring:

65.00 g of titanium dioxide pigment¹²⁾

5.00 g of aluminum silicates¹³⁾

215.00 g of calcium carbonate, calcite (about 5 μm)¹⁴⁾

55.00 g of calcium carbonate, precipitated, 0.3 μm¹⁵⁾

95.00 g of calcium carbonate, chalk, 2.4 μm¹⁶⁾

65.00 g of talc/dolomite, 6 μm¹⁷⁾.

12) Kronos®2043 from Kronos Titan GmbH, Leverkusen

13) Aluminum silicate P 820 from Degussa AG, Frankfurt

14) Calcite, average particle size 5 μm; Omyacarb 5GU from Omya GmbH,Cologne

15) Socal P2 from Deutsche Solvay GmbH, Solingen.

16) Omya Violette Etikette from Omya GmbH, Cologne

17) Talc/dolomite, average particle size 6 μm; Naiatsch SE-Micro fromLuzenac Deutschland GmbH, Düsseldorf

The components were mixed in a disperser, then the followingconstituents were added with stirring: 130.00 g of dispersion, 50% byweight, and 70.00 g of water.

The solids content of the paint was 57% by weight. The pigment volumeconcentration was 75%. The performance properties are summarized inTable 5.

3. Solventborne interior paint with a pvc of 81% formulation III(Comparative Examples C8 and C9 and Inventive Example 7)

A vessel was charged with the following constituents:

100.00 g of water

2.00 g of dispersing auxiliary²⁾

7.00 g of aqueous solution of a sodium polyphosphate²²⁾

2.00 g of concentrated ammonia solution

3.00 g of preservatives¹⁰⁾

150.00 g of 2% strength by weight aqueous methylhydroxyethylcellulosesolution¹⁸⁾

12.00 g of white spirit K 60¹⁹⁾ and

12.00 g of plasticizer²⁰⁾.

2) 30% strength by weight aqueous solution of an ammonium polyacrylate;Pigmentverteiler [pigment dispersant] A from BASF AG, Ludwigshafen

22) Calgon® from BK Ladenburg, Ladenburg

10) Parmetol®A23 from Schulke & Mayr GmbH, Norderstedt

18) MN 20000 GB, Wolff Walsrode GmbH, Walsrode

19) Boiling range 180-210° C., Esso Chemie GmbH, Cologne.

20) Diisobutyl ester of a mixture of C₄-C₆ dicarboxylic acids, Lusolvan®FBH, BASF AG

The following constituents were added with stirring:

71.00 g of titanium dioxide pigment¹²⁾

12.00 g of aluminum silicate¹³⁾

83.00 g of calcium carbonate, precipitated, 0.3 μm¹⁵⁾

417.00 g of calcium carbonate, calcite 5 μm¹⁴⁾

12) Kronos®2043 from Kronos Titan GmbH, Leverkusen

13) Aluminum silicate P 820 from Degussa AG, Frankfurt

15) Socal P2 from Deutsche Solvay GmbH, Solingen.

14) Calcite, average particle size 5 μm; Omyacarb 5GU from Omya GmbH,Cologne

The components were mixed with one another in a high-speed mixer andthen the following constituents were added with stirring:

4.00 g of wetting agent²¹⁾

3.00 g of defoamer¹¹⁾

102.00 g of dispersion (50% by weight)

20.00 g of water.

21) Lumiten N-OC from BASF AG, 30% strength by weight solution of afatty alcohol ethoxylate, cloudpoint in aqueous sodium chloridesolution: 90° C.

11) Agitan 280 from Münzing-Chemie GmbH, Heilbronn

The pvc of the paint was 81%. The results of performance testing aresummarized in Table 6.

III. Determining the Performance Properties

1. Abrasion Resistance

For the formulation I the abrasion resistance was determined inaccordance with ASTM D 2486 using a Gardner abrasion machine and astandardized abrasive medium (abrasive type SC-2).

The emulsion paints of formulation I were applied with a box-typecoating bar (gap height 175 μm, 7 MIL) to Leneta sheets. The sheets werethen dried in a climatically controlled chamber for 14 days understandard climatic conditions (23° C., 50% relative atmospherichumidity). The dry coat thickness was about 50 μm.

For each emulsion paint the abrasion test was carried out on 3 sheets.For this purpose, a metal strip 250 μm thick was placed underneath thecenter of the sheet. Abrasive paste was then applied, and abrasion wascarried out with a nylon brush until the coating had been abraded rightthrough at the point lying above the metal. The parameter indicated isthe number of double strokes required to bring about this completeabrasion at one point. It is stated as the average of two values whichdeviate by less than 25%.

The emulsion paints of formulation II were tested for their abrasionresistance in accordance with DIN 53778 sheet 2; a 60 mm wide coatingbar was used to apply a coating film to a Leneta sheet of approximately430×80 mm. The gap height was chosen so as to give a dry coat thicknessof 100 μm. The film was dried under standard climatic conditions for 28days. Then an abrasion brush was guided over the coating in an abrasiondevice with continuous dropwise addition of a 0.25% strength aqueoussolution of sodium n-dodecylbenzene-sulfonate. The number of doublestrokes until the coating was abraded right through was used as theparameter for the wet abrasion resistance.

The emulsion paints from III were likewise tested for their wet abrasionresistance in accordance with DIN 53778. In deviation from the aboveprocedure, however, the formulation was applied in a wet coat thicknessof 280 μm. The coating was dried at 50° C. for 2 days and then understandard climatic conditions for a further 5 days.

2. Blocking Resistance

The blocking resistance was determined in accordance with ASTM D 4946.For this purpose the emulsion paints from II were applied with abox-type coating bar (3 MIL, gap height 75 μm) to Leneta sheets. Thesheets were then dried for 24 hours under standard climatic conditions.The dried and coated sheets were subsequently cut into 3.8 cm squares.The squares were placed on top of one another with the coated sidesfacing and were inserted between two glass plates. A weight of 2 kg wasplaced on top of these glass plates. This arrangement was stored at 50°C. for 24 hours. The sheets were then investigated for their partingbehavior. The results were based on a rating scale from 0 to 10:

0=75 to 100% tearing of the coating

1=50 to 75% tearing

2=25 to 50% tearing

3=5 to 25% tearing

4=very tacky: 0 to 5% tearing;

5=moderate tack

6=slight tack

7=slight to very slight tack

8=very slight tack

9=barely any tack

10=no tack

3. Wet Adhesion

The wet adhesion was determined as follows: In a first step the Lenetasheets were coated with a solventborne alkyd resin lacquer (Glasurit EA,high-gloss lacquer from BASF deco GmbH, Cologne) using a box-typecoating bar (gap height 180 μm). The sheets were dried for 24 hours in astandard-climate chamber and then in an oven at 50° C. for 14 days. Theemulsion paints from II were then applied to the resin-coated Lenetasheets as a second coating, using an applicator (gap height 250 μm, 10MIL). The resulting sheets were dried under standard climatic conditionsfor 3 days. Three test specimens were cut from each sheet. Each testspecimen was scribed horizontally using a razorblade, and then afreeze/thaw test was conducted. For this test the specimens were wettedwith water and subsequently stored in a deep freeze at −20° C. for 16hours. This procedure was repeated twice. The samples were then allowedto warm to room temperature in water. Thereafter, the adhesion of thecoating at the scribe mark was assessed by scratching with thefingernail, on the basis of a rating scale from 0 to 5, where 0 denotesoptimal adhesion and 5 denotes no adhesion (flawless removal). Theratings 1 to 4 denote intermediate values.

TABLE 3 Performance testing of the formulation I (single-stage polymers)Block- Wet ing abrasion Disper- Acid¹⁾ MFT²⁾ resis- Wet resis- Examplesion [% by wt.] [° C.] tance adhesion tance C1 CD1 MAA; 2 6.0 10 2 1200C2 CD2 IA; 2 4.0 10 2 1000 C3 CD3 IA; 2 2.0 10 3 1325 1 D1 IA; 1 2.0 102 2000 2 D2 IA; 1 4.0 10 3 1700 3 D3 IA; 0.75 2.0 10 3 2200 ¹⁾% byweight based on the overall weight of the polymer: MAA = methacrylicacid, IA = itaconic acid ²⁾minimum film-forming temperature

TABLE 4 Performance testing of the formulation I (two-stage polymers)Block- Wet ing Wet abrasion Disper- Acid¹⁾ MFT²⁾ resis- ad- resis-Example sion [% by wt.] [° C.] tance hesion tance C4 CD4 AA; 0.75 13.0 93 1270 C5 CD5 MAA; 0.75 10.0 10 3 1330 4 D4 IA; 0.75 9.0 10 3 2800 5 D5IA; 0.5  12.0 10 4 2200 AA; 0.25 ¹⁾% by weight, based on the overallweight of the polymer: AA = acrylic acid, MAA = methacrylic acid, IA =itaconic acid ²⁾minimum film-forming temperature

TABLE 5 Performance testing of the formulation II Acid Wet abrasionExample Dispersion [% by wt.]¹⁾ resistance C6 CD6 AA; 1 2350 C7 CD7 MAA;1 2670 6 D6 IA; 1 4660 ¹⁾% by weight, based on the overall weight of thepolymer: AA = acrylic acid, MAA = methacrylic acid, IA = itaconic acid

TABLE 6 Performance testing of the formulation III Acid Amide Wetabrasion Example Dispersion [% by wt.]¹⁾ [% by wt.]²⁾ resistance C8 CD8MAA; 2.6 AM; 1.4 1320 C9 CD9 AA; 2.6 AM; 1.4 1336 7 D7 IA; 1.0 — 3113¹⁾% by weight, based on the overall weight of the polymer: AA = acrylicacid, MAA = methacrylic acid, IA = itaconic acid ²⁾% by weight, based onthe overall weight of the polymer: AM = acrylamide

What is claimed is:
 1. An emulsion paint, comprising: i) a polymericbinder, which comprises at least one copolymer P of ethylenicallyunsaturated monomers M in the form of an aqueous polymer dispersion; ii)at least one inorganic pigment; iii) an inorganic filler/extender; andiv) an auxiliary; wherein said copolymer P has a glass transitiontemperature Tg in the range of from −10 to +50° C.; and wherein saidcopolymer P consists of the following units in polymerized form a) 20 to80% by weight of at least one monomer M2a, whose homopolymer has a glasstransition temperature of >30° C., and which is selected from the groupconsisting of styrene, α-methylstyrene, methyl methacrylate, ethylmethacrylate, n-propyl methacrylate, iso-propyl-methacrylate, n-butylmethacrylate, iso-butyl methacrylate, tert-butyl metracrylate, vinylacetate, acrylonitrile and metacrylonitrile; b) 20 to 79.7% by weight ofat least one monomer M2b, whose homopolymer has a glass transitiontemperature of <20° C. and which is selected from the group consistingof C₁-C₁₂-alkyl acrylates, butadiene, vinyl versatates, ethyl acrylate,n-butyl acrylate, and 2-ethylhexyl acrylate; c) 0.5 to 1.5% by weight ofc1) a first acidic monomer M1 selected from the group consisting ofitaconic acid, a salt of itaconic acid, an anhydride of itaconic acid,and mixtures thereof, or c2) mixtures of said first acidic monomer with0 to 0.75% by weight of a second acidic monomer selected from the groupconsisting of acrylic acid and methacrylic acid, provided that a totalamount of said first acidic monomer and said second acidic monomer isfrom 0.5 to 1.5% by weight, based on a total weight of said copolymer P;and a weight ratio of said second acidic monomer to said fit acidicmonomer does not exceed 1:1; and d) 0.2 to 5% by weight of at least onemonomer M3 having at least one urea group; wherein a sum of the amountsof monomers M1, M2a, M2b and M3 is 100% by weight; wherein said emulsionpaint contains no cross-linking additive.
 2. The emulsion paintaccording to claim 1, wherein itaconic acid is the sole acidic monomerM1.
 3. The emulsion paint according to claim 1, wherein said aqueousdispersion of the copolymer P is obtained by free-radical aqueousemulsion polymerization of the monomers M using a monomer feed processin which all of said acidic monomer M1 is present in the monomer feed.4. The emulsion paint according to claim 1, with a pigment volumeconcentration (pvc) >10%.
 5. A method of improving the wet abrasionresistance of a polymer-bound coating composition, comprising: mixing acopolymer as a binder with said coating composition; wherein saidcopolymer consists of the following units in polymerized form a) 20 to80% by weight of at least one monomer M2a, whose homopolymer has a glasstransition temperature of >30° C., and which is selected from the groupconsisting of styrene, α-methylstyrene, ethyl methacrylate, n-propylmethacrylate, iso-propyl-metacrylate, n-butyl methacrylate, iso-butylmethacrylate, tert-butyl methacrylate, vinyl acetate, acrylonitrile andmethacrylonitrile; b) 20 to 79.7% by weight of at least one monomer M2b,whose homopolymer has a glass transition temperate of <20° C., and whichis selected from the group consisting of C₁-C₁₂-alkyl acrylates,butadione, vinyl versatates, ethyl acrylate, n-butyl acrylate, and2-ethylhexyl acrylate; c) 0.5 to 1.5% by weight of c1) a first acidicmonomer M1 selected from the group consisting of itaconic acid, a saltof itaconic acid, an anhydride of itaconic acid, and mixtures thereof,or c2) mixtures of said first acidic monomer with 0 to 0,75% by weightof a second acidic monomer selected from the group consisting of acrylicacid and methacrylic acid, provided that a total amount of said firstacidic monomer and said second acidic monomer is from 0.5 to 1.5% byweight, based on a total weight of said copolymer P; and a weight ratioof said second acidic monomer to said first acidic monomer does notexceed 1:1; and d) 0.2 to 5% by weight of at least one monomer M3 havingat least one urea group; wherein a sum of the amounts of monomers M1,M2a, M2b and M3 is 100% by weight; wherein said binder and said coatingcomposition contains no cross-linking additive.
 6. The method accordingto claim 5, wherein the coating composition is an emulsion paint.
 7. Theemulsion paint as claimed in claim 1, wherein said second acidic monomeris present; and wherein a total amount of said first acidic monomer andsaid second acidic monomer is from 0.5 to 1.0% by weight based on atotal weight of said copolymer P; and provided that a weight ratio ofsaid monoethylenically unsaturated carboxylic acid to said acidicmonomer does not exceed 1:1.
 8. The emulsion paint as claimed in claim1, wherein the aqueous dispersion of the copolymer P is obtained byfree-radical aqueous emulsion polymerization of the monomers M using amonomer feed process in which all of the itaconic acid is present in themonomer feed.
 9. The emulsion paint as claimed in claim 1, wherein theaqueous dispersion of the copolymer P is obtained by free-radicalaqueous emulsion polymerization of the monomers M using a monomer feedprocess in which at least 50% by weight of acidic monomer M1 are presentin the monomer feed.
 10. The emulsion paint as claimed in claim 1,wherein the aqueous dispersion of the copolymer P is obtained byfree-radical aqueous emulsion polymerization of the monomers M using amonomer feed process in which at least 50% by weight of the itaconicacid are present in the monomer feed.
 11. The emulsion paint accordingto claim 1, with a pigment volume concentration (pvc) >40%.
 12. Theemulsion paint according to claim 1, with a pigment volume concentration(pvc) >60%.
 13. The emulsion paint according to claim 1, wherein anamount of itaconic acid in said copolymer P is from 0.5 to 0.9% byweight, based on a total weight of said copolymer P.
 14. The emulsionpaint according to claim 1, wherein a weight ratio of said second acidicmonomer to said first acidic monomer does not exceed 1:2.
 15. Theemulsion paint according to claim 1, wherein a weight ratio of saidsecond acidic monomer to said first acidic monomer does not exceed 1:3.16. The emulsion paint according to claim 1, wherein a weight ratio ofsaid second acidic monomer to said first acidic monomer does not exceed1:9.
 17. The emulsion paint according to claim 1, further comprising, incopolymerized form, 0 to 1% by weight of monomers M4 which comprisesiloxane groups.
 18. The emulsion paint according to claim 17, whereinsaid monomers M4 are selected from the group consisting ofvinyltrialkoxysilanes, alkylvinyldialkoxysilanes and(meth)acryloxyalkyltrialkoxysilanes.
 19. The emulsion paint according toclaim 1, having a wet abrasion resistance of from 1700 to
 4660. 20. Theemulsion paint according to claim 19, having a wet abrasion resistanceof from 2800 to
 4660. 21. An emulsion paint, comprising: i) a polymericbinder, which comprises at least one copolymer P of ethylenicallyunsaturated monomers M in the form of an aqueous polymer dispersion; ii)at least one inorganic pigment; iii) an inorganic filler/extender; andiv) an auxiliary; wherein said copolymer P has a glass transitiontemperature Tg in the range of from −10 to +50° C.; and wherein saidcopolymer P consists of the following units in copolymerized form i) 20to 80% by weight of at least one monomer M2a, whose homopolymer has aglass transition temperature of >30° C., and which is selected from thegroup consisting of styrene, α-methylstyrene, methyl methacrylate, ethylmethacrylate, ethyl methacrylate, n-propyl methacrylateiso-methacrylate, n-butyl methacrylate, iso-butyl methacrylate,tert-butyl methacrylate, vinyl acetate, acrylonitrile andmethacrylonitrile; ii) 20 to 79.7% by weight of at least one monomerM2b, whose homopolymer has a glass transition temperature of <20° C.,and which is selected from the group consisting of C₁-C₁₂-alkylacrylates, butadiene, vinyl versatates, ethyl acrylate, n-butylacrylate, and 2-ethylhexyl acrylate; iii) 0.5 to 1.0% by weight ofitaconic acid as monomer M1; and iv) 0.2 to 5% by weight of at least onemonomer M3 having at least one urea group; wherein a sum of the amountof monomers M1, M2a, M2b and M3 is 100% by weight; wherein saidcopolymer P contains no polymerized acrolein; wherein said emulsionpaint contains no cross-linking additives.
 22. The emulsion paintaccording to claim 21, wherein said monomer M2a is selected from thegroup consisting of methyl methacrylate, n-butyl methacrylate andstyrene; and wherein said monomer M2b is selected from the groupconsisting of C₁-C₁₂ alkylacrylates.
 23. A method of improving a wetabrasion resistance of a polymer bound emulsion paint, comprising;mixing an aqueous dispersion of a copolymer P as a binder into a latexpaint which additionally comprises at least one inorganic pigment, aninorganic filler extender and an auxilliary; wherein said copolymer Pcomprises in polymerized form a) as monomer M 1: 0.5 to 1.0% by weightof an acidic monomer selected from the group consisting of itaconicacid, a salt of itaconic acid an anhydride of itaconic acid and acombination thereof, and 0 to 0.5% by weight of a second monomerselected from the group consisting of acrylic acid and methacrylic acidbased on a total weight of said copolymer P; provided that a totalamount of said acidic monomer and said second monomer is from 0.5 to1.0% by weight, based on the total weight of said copolymer P, and theweight ratio of said second monomer to said acidic monomer does notexceed 1:1; b) 90 to 99.9% by weight of monomers M2 selected from thegroup consisting of vinylaromatic monomers, esters of ethylenicallyunsaturated C₃-C₈ monocarboxylic acids with C₁-C₁₂-alkanols, and vinylesters of aliphatic C₁-C₁₂ monocarboxylic acids, based on a total amountof said copolymer P; and c) 0.1 to 10% by weight of at least one monomerM3 which comprises an urea group, based on the total weight of copolymerP; and wherein said aqueous polymer dispersion contains no polymerizedacrolein; ii) at least one inorganic pigment, iii) an inorganic filleror an inorganic extender; and iv) an auxiliary; wherein said aqueousdispersion or said latex paint contains no cross-linking additive. 24.The method according to claim 23, wherein said copolymer P is the onlybinder.
 25. The method according to claim 23, wherein said emulsionpaint has a pigment volume concentration of >10%.
 26. The methodaccording to claim 23, wherein said emulsion paint has a pigment volumeconcentration of >40%.
 27. The method according to claim 23, whereinsaid emulsion paint has a pigment volume concentration of >60%.
 28. Themethod according to claim 23, wherein said copolymer P comprises incopolymerized form i) 20 to 80% by weight of at least one monomer M2a,whose homopolymer has a glass transition temperature of >30° C., andwhich is selected from the group consisting of styrene, α-methylstyrene,methyl methacrylate, ethyl methacrylate, n-propyl methacrylate,iso-propyl-methacrylate, n-butyl methacrylate, iso-butyl methacrylate,tert-butyl methacrylate, vinyl acetate, acrylonitrile andmethacrylonitrile; ii) 20 to 79.7% by weight of at least one monomerM2b, whose homopolymer has a glass transition temperature of <20° C.;iii) 0.5 to 1.0% by weight of itaconic acid as monomer M1; and iv) 0.2to 5% by weight of at least one monomer M3 having at least one ureagroup; wherein a sum of the amounts of monomers M1, M2a, M2b and M3 is100% by weight.
 29. The method according to claim 23, wherein a wetabrasion resistance of from 1700 to 4660 is achieved.
 30. The methodaccording to claim 23, wherein a wet abrasion resistance of from 2800 to4660 is achieve.
 31. An emulsion paint, comprising: i) a polymericbinder, which comprises at least one copolymer P of ethylenicallyunsaturated monomers M in the form of an aqueous polymer dispersion;wherein said copolymer P has a glass transition temperature Tg in therange of from −10 to +50° C.; and wherein said copolymer P comprises inpolymerized form a) as monomer M 1: 0.5 to 1.0% by weight of an acidicmonomer selected from the group consisting of itaconic acid, a salt ofitaconic acid an anhydride of itaconic acid and a combination thereof,and 0 to 0.5% by weight of a second monomer selected from the groupconsisting of acrylic acid and methacrylic acid based on a total weightof said copolymer P; provided that a total amount of said acidic monomerand said second monomer is from 0.5 to 1.0% by weight, based on thetotal weight of said copolymer P, and the weight ratio of said secondmonomer to said acidic monomer does not exceed 1:1; b) 90 to 99.9% byweight of monomers M2 selected from the group consisting ofvinylaromatic monomers, esters of ethylenically unsaturated C₃-C₈monocarboxylic acids with C₁-C₁₂-alkanols, and vinyl esters of aliphaticC₁-C₁₂ monocarboxylic acids based on a total amount of said copolymer P;and c) 0.1 to 10% by weight of at least one monomer M3 which comprisesan urea group, based on the total weight of copolymer P; and whereinsaid aqueous polymer dispersion contains no polymerized acrolein; ii) atleast one inorganic pigment, iii) an inorganic filler or an inorganicextender; and iv) an auxiliary; wherein said emulsion paint contains nocross-linking additive.
 32. The emulsion paint according to claim 1,wherein said unit c1) is present.
 33. The emulsion paint according toclaim 1, wherein said unit c2) is present.
 34. The emulsion paintaccording to claim 17, wherein said monomer M4 is present.
 35. Theemulsion paint according to claim 1, where said auxiliary is selectedfrom the group consisting of wetting agents, thickeners, defoamers,preservatives, hydrophobizing agents, biocides, fibers, film-formingauxiliaries and solvent.
 36. The emulsion paint according to claim 1,wherein said emulsion paint further comprises water.
 37. The emulsionpaint according to claim 31, wherein said monomers M comprise at leastone monomer M2a, whose homopolymer has a glass transition temperatureof >30° C., and which is selected from the group consisting of styrene,α-methylstyrene, methyl methacrylate, ethyl methacrylate, n-propylmethacrylate, iso-propyl -methacrylate, n-butyl methacrylate, iso butylmethacrylate, tert-butyl methacrylate, vinyl acetate, acrylonitrile andmethacrylate; and at least one monomer M2b, whose homopolymer has aglass transition temperature of <20° C., and winch is selected from thegroup consisting of C₁-C₁₂-alkyl acrylates, butadiene, vinyl versatates,ethyl acrylate, n-butyl acrylate, and 2- ethylhexyl acrylate.